Spark is a relatively new manufacturer, best known for their relatively floody headlamps (with direct support for Li-ions), and more recently handhelds. In this review, I will be examining their current 1xAA/14500 headlamp, with a Neutral White emitter (ST5-190NW). Please see my SL6 review for a handheld comparison.

Manufacturer Specifications:

LED: Cree XML cool white T6

5 constant output modes

Super: 220lm 0.9hours

Max: 120lm 1.8 hours

Med2: 36lm 8 hours

Med1: 10lm 30 hours

Low: 2lm 86 hours

Battery: One 14500 rechargeable Li battery or AA battery with range from 1.0V to 4.2V (Battery not included)

Hold on button to go through Minimum, Medium 1& Medium 2, Max modes. When desire mode is reached, release to stop brightness ramping and current mode is memorized. (AA with short term memorization, 14500 with permanent memorization)

The build of the Spark ST5 headlamp is distinctive, but still familiar looking. The protruding forward head does make it a bit easier to locate the button. The headband is good quality, and worked well in my testing. It holds the light securely (both within the holder, and strapped to your head), but still allows for accurate positioning.

I like the muted gray natural anodizing (manufacturer claims hard anodized). There are some ridges in the anodizing on my sample, but the overall effect is still good (think naturally-weathered looking). Anodizing does seem fairly thinly coated, however.

Labels are fairly minimal and small, but clearly legible against the background.

There is only knurling on the end pieces, once of which opens up to allow you to insert the AA battery. Screw threads are anodized for tailcap lock-out.

There was often a brief full-power pre-flash upon connection of the battery cap with the body and battery on my sample.

The switch is an electronic switch, with a typical traverse (although there is a clear soft click when making contact). Feel is similar to other Spark or Zebralight electronic switches.

Light can't really "tailstand" as such, but with a battery installed there is enough of a counter-balance to let you stand it up on its flat edges.

I like the included frosted glass diffuser (feels like glass, not plastic). This can be used to replace the clear lens, but I find it also fits over the existing lens assembly if you don't want to open everything up (i.e. just unscrew the bezel and pop on top). Note the bezel ring doesn't screw down all the way with both lenses in place, of course.

The ST5 has a shallow reflector (light OP coating), which – when coupled with the XM-L emitter – suggests the light will not be a great thrower. XM-L emitter was well centered on my sample.

Which brings me to the white-wall beamshots. Unless otherwise identified, all lights are on max output on 1x Sanyo Eneloop NiMH, about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). For 14500, I used an AW protected cell. "Daylight" white balance used on my Canon S5, to better show tint differences of my Neutral White emitters. All beamshots taken immediately upon activation.

Let's start with un-diffused white beams:

As expected, the default Spark ST5 produced a nice beam, with a fairly broad hotspot that wasn't overly throwy. Even without a diffuser, I found this beam quite good for up-close work (i.e. better than the XP-E-equipped lights). Note that although the original Petzl Tikka XP had an optic that produce a nice focused beam, the XP-E-equipped Tikka XP2 is rather ringy in comparison (especially on the periphery).

Here are some comparison shots with diffusers in place:

User Interface

The Spark ST5 has a similar user interface to other Spark lights (which are in turn similar to the Zebralights).

A quick click-release of the switch activates the light.

On all batteries, there are four modes which can be accessed sequentially by holding down the switch (and letting go when the mode you want is reached). These are Lo – Med1 – Med2 – Hi, in repeating sequence.

On 3.7V 14500 Li-ion, there is a fifth constant output mode called Super Hi. This is accessed by double-clicking the switch in any mode.

There are no strobe/SOS modes on the ST5.

The ST5 has mode memory, and remembers the last level used when re-activating the light. Unlike the SL6, this memory is retained even if you unscrew the tailcap (i.e. ST5 recalls the last setting after a battery change). The ST5 manual claims this only happens on 14500, but I found it occurred on NiMH as well.

Like the SL6, there is a timing quirk when turning on – you need to be quick on the press to activate the light. If you hold the switch for too long before releasing (i.e., half a second, as you might on a standard clicky), the light turns on and shuts off immediately. This is apparently an intentional (but undocumented) design feature, to allow for momentary signaling. While it works for this purpose, it is a bit tricky, as you need to get the timings just right (i.e. quick release for sustained on, longer hold before release for momentary on-off, and an even longer hold for ramping).

PWM/Strobe

Like the SL6, the output modes on the ST5 current-controlled. At the lower levels (Lo, Med1), I detected high frequency noise:

Med1:

Lo:

On the related SL6, I saw a lot of similar high frequency noise on these levels. HKJ believes the SL6 is still current-regulated at the Lo/Med1 levels - but given the difficulties in providing high current regulation at a low current, the circuit overcompensates and produce a lot of high-frequency noise.

Presumably the same is happening here, even though it looks like this noise has a re-occuring pattern around ~14kHz on Med1 and ~6kHz on Lo. But Spark confirms the lights don't use PWM, so it seems HKJ's conclusions are correct. In any case, this noise is completely undetectable by eye - you will not be able to observe any flickering on the lower outputs on the ST5.

There are no strobe/SOS modes on the ST5.

Standby Current Drain

Due to the electronic switch nature of the light, the ST5 has a constant parasitic stand-by current drain when the tailcap is connected. Unlike the SL6 (where the dual-switch design prevents an accurate reading), I was able to measure my ST5 standby drain at 13.2uA on NiMH and 41.6uA on 14500. That translates into over 17 years on a standard 2000mAh NiMH, and over 2 years on 750mAh 14500.

As always, this current can be cut by simply unscrewing the tailcap a quarter turn when the light is not in use (which I recommend for all lights with a standby drain). Unlike the SL6, last output memory is maintained on the ST5 even after disconnecting the battery.

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1.htm for a description of the terms used in these tables.

First, a comparison to my other headlamps:

And now, other 1xAA lights:

Consistent with its role as a small-mass headlamp, the ST5 is not as bright on max settings as larger handheld XM-L lights, on either battery type. But it is very bright by headlamp standards. The beam is not as throwy as some XP-E-based lights, but that actually suits my general headlamp purposes better anyway.

Output/Runtime Comparison:

Output/runtime efficiency is exactly what you would expect for a good current-controlled XM-L light driven to these levels.

Potential Issues

Switch timing takes a little getting used. Standard length click-release is "momentary mode", causing the light turn on/off for signalling. You need to be quick on the release for sustained on, or hold longer to activate the ramp.

Need to unscrew the bezel to swap or add the diffuser.

High output pre-flash often seen when connecting the tailcap to the battery/body tube.

Preliminary Observations

I like a nice headlight, and the Spark ST5 performs well in this regard. The ergonomics are good, and the light (and headstrap) are easy to access and use.

In the interest of full disclosure, my usual go-to headlamp is a four-year Petzl Tikka XP that I long ago modded from a Lux to an SSC (gives a good beam with decent burst mode, and has optional colored diffusers). If I know I won't need the diffuser, I usually grab the neutral-tinted Zebralight H31w instead. Both lights are good, but neither is perfect in my view.

I had the opportunity to test the ST5 out in some home plumbing repairs, and it worked great (typically used Med1 the most, but Lo and Med2 also saw some action). Thanks to the larger die XM-L emitter, I found the beam to have a larger hotspot than the XP-E headlamps (which are fine, but XP-E is not my preferred emitter choice in this venue). As a result, I didn't really feel the need to use the diffuser on the ST5 (something I often go for in close quarters on other headlamps).

The overall switch feel, UI and circuit functioning is reminiscent of the Zebralight lights, but with some specific differences in shortcuts and timings. I imagine it would be a tough choice between the ST5 and an equivalent model Zebralight. One point in the ST5's favour is the symmetrical design with direct centre beam and button. This saves potentially awkward reaching with the wrong hand on the lateralized Zebralight (i.e. emitter is at one end). May not be an issue for you, but I'm somewhat ambidextrous for most tasks, so it's a 50:50 chance which hand reaches up to feel for the button. Similar issue with the buttons on the old Tikka XP – I favour a single center button whenever possible.

My only concern with center-beam lights is how far forward they face (i.e. I don't want reflections picked up by my glasses, or too much of a spotbeam-effect up close). I've found a bit of the spotbeam effect with the ITP H01, but that’s likely due to the smaller head and XP-E emitter. No issues with the ST5 so far.

Performance-wise, the ST5 has excellent runtimes for the output, as expected on a current-controlled light. Whatever the source of high frequency noise on the lowest modes, it is not visible by eye (I am sensitive to PWM-like flicker, and there is no sign of it here). The ST5 was a pleasure to use at all output levels.

Unless I need red light, for the next little while I'm going to stick with the ST5 for my headlamp needs. I'll post back any updated findings as I have them.

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